Mass market vehicle seats generally include padded upholstery around a framework. The frameworks are generally complicated, allowing for adjustment of the seat. Such vehicle seats are usually not adapted to resist large lateral forces on an occupant of the seat, or to be fixed to a vehicle roll cage.
In vehicle seats for racing cars that, weight is very important. This makes complex framework undesirable. Also, users of seats in motor sports are likely to experience large lateral forces because of cornering at high speeds, loss of control of the vehicle or collisions.
Vehicle seats with forwardly extending side portions are known. Generally these side portions extend only a short distance from the seat's backrest and so do not effectively restrain lateral movement of the driver. One such seat is described in U.S. Pat. No. 3,627,379. This seat includes triangular side portions that are widest at the top, formed from a tubular framework. As shown in FIG. 3, the side portions are padded to a laterally sloping shape, such that the ability of the seat to resist lateral forces on the driver is not strong. Furthermore, this structure is comparatively complicated and heavy. A similar seat is described in U.S. Pat. No. 4,679,854. Again the “side restraints” do not extend far from the seat back.
U.S. Pat. No. 5,513,897 discloses a vehicle seat with a lateral head restraint. Again, this seat is a complicated structure. The seat does not provide lateral support other than around the head. US 2002/0038966 describes a safety seat with head protection members but not shoulder restraints.